I ran this through my debugger, and my assumptions where correct. The
FLAG_NEW_VERSION flag is set while versionManager is null. I'm, looking
around and can't figure out the exact conditions that would cause this.
Any thoughts?
Aaron
Aaron Hiniker wrote:
> Yeah, I know. But I'm not messing with any versioning settings (this
> is just out-of-the-box ajax components and the like), so really there
> shouldn't be any of these issues, correct? Here's
> mayTrackChangesFor() method, I've added a comment regarding my
> thoughts as to what is causing this:
>
> private final boolean mayTrackChangesFor(final Component
> component, MarkupContainer parent)
> {
> // Auto components do not participate in versioning since they are
> // added during the rendering phase (which is normally illegal).
> if (component.isAuto() || (parent == null &&
> !component.isVersioned())
> || (parent != null && !parent.isVersioned()))
> {
> return false;
> }
> else
> {
> // the component is versioned... are we tracking changes
> at all?
> if (getFlag(FLAG_TRACK_CHANGES)) <-- this returns true
> {
> // we are tracking changes... do we need to start new
> version?
> if (!getFlag(FLAG_NEW_VERSION)) <-- this may return
> false?
> {
> // if we have no version manager
> if (versionManager == null)
> {
> // then install a new version manager
> versionManager = newVersionManager();
> }
>
> // start a new version
>
> versionManager.beginVersion(getRequest().mergeVersion());
> setFlag(FLAG_NEW_VERSION, true);
> }
>
> // this returns true, even though versionManager is
> not set because of false check above
> // return true as we are ready for versioning
> return true;
> }
>
> // we are not tracking changes or the component not versioned
> return false;
> }
> }
>
> Should I specifically be setting versioning/non-versioning for
> components to avoid this error?
>
> Aaron
>
> Johan Compagner wrote:
>> But if it is null then you could have a problem that things should be
>> versioned but arent..
>>
>> So adding null checks is not the fix.
>>
>> johan
>>
>>
>> On 3/2/07, * Aaron HIniker* <[EMAIL PROTECTED]
>> <mailto:[EMAIL PROTECTED]>> wrote:
>>
>> That's why I was pointing at mayTrackChangesFor().. I looked at
>> the method and I can't see a loophole, but there must be one to
>> generate an NPE, correct?
>>
>> When I implemented the not-null check, I noticed exceptions still
>> being thrown from 2 other methods (if you search Page.java for
>> versionManager, you can see where there is the assumption that
>> mayTrackChangesFor() is checked for 'true', yet versionManager is
>> never initialized in other methods as well. So after adding the
>> null check to each of these methods, the application is working
>> fine. Thing is, I've only seen this exception when dealing with
>> ajax (default not versioned, right?).
>>
>> I will try and run a debugger through mayTrackChangesFor() with
>> my current app, and see the logic flow and why versionManager is
>> ending up null.
>>
>> Aaron
>>
>> Johan Compagner wrote:
>>> That is because the mayTrackChangesFor() method should only
>>> return true
>>> when it makes a version manager. Why is that not the case?
>>> If that method returns true the version manager can't be null
>>> because the version info must be tracked.
>>>
>>> johan
>>>
>>>
>>> On 3/1/07, *Aaron Hiniker* <[EMAIL PROTECTED]
>>> <mailto:[EMAIL PROTECTED]>> wrote:
>>>
>>> I pulled the latest from trunk. And I am getting this NPE:
>>>
>>> 16:30:14,543 ERROR [STDERR] java.lang.NullPointerException
>>> 16:30:14,544 ERROR [STDERR] at
>>> wicket.Page.componentStateChanging(Page.java:327)
>>> 16:30:14,545 ERROR [STDERR] at
>>> wicket.Component.addStateChange(Component.java:2553)
>>> 16:30:14,545 ERROR [STDERR] at
>>> wicket.Component.setModel(Component.java:2191)
>>> 16:30:14,545 ERROR [STDERR] at
>>> wicket.MarkupContainer.setModel(MarkupContainer.java :596)
>>> 16:30:14,546 ERROR [STDERR] at
>>>
>>> com.edicorp.erp.web.components.search.ProductSearchPanel.query(ProductSearchPanel.java:144)
>>> 16:30:14,546 ERROR [STDERR] at
>>> com.edicorp.erp.web.components.search.ProductSearchPanel.onUpdate
>>> (ProductSearchPanel.java:109)
>>> 16:30:14,546 ERROR [STDERR] at
>>>
>>> com.edicorp.erp.web.components.search.FilterPanel.fireOnChange(FilterPanel.java:74)
>>> 16:30:14,547 ERROR [STDERR] at
>>>
>>> com.edicorp.erp.web.components.search.query.QueryPanel$QueryForm.onSubmit
>>> (QueryPanel.java:197)
>>> 16:30:14,547 ERROR [STDERR] at
>>> wicket.markup.html.form.Form.delegateSubmit(Form.java:680)
>>> 16:30:14,547 ERROR [STDERR] at
>>> wicket.markup.html.form.Form.onFormSubmitted(Form.java:396)
>>> 16:30:14,547 ERROR [STDERR] at
>>> sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
>>>
>>>
>>> I remember I was getting this NPE before, and I patched the
>>> source to
>>> include this null check in Page.java :
>>>
>>> final void componentStateChanging(final Component
>>> component,
>>> Change change)
>>> {
>>> checkHierarchyChange(component);
>>>
>>> dirty();
>>> if (mayTrackChangesFor(component, null))
>>> {
>>> if ( versionManager != null )
>>>
>>> versionManager.componentStateChanging(change);
>>> }
>>> }
>>>
>>> It seems that everywhere else in Page.java there is a null
>>> check for
>>> versionManager, except in this method. Not sure, but
>>> perhaps the
>>> problem lies in the #mayTrackChangesFor() method, but in any
>>> case if I
>>> add this null check my code runs fine.
>>>
>>> Aaron
>>>
>>>
>>>
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